Toad

About: Toad is a research topic. Over the lifetime, 1624 publications have been published within this topic receiving 28732 citations.

Prostaglandins and toad spinal cord responses.

Abstract: PROSTAGLANDINS have a wide distribution in the vertebrate body and have been shown to be pharmacologically active on many types of vertebrate tissues. Evidence that these compounds have a neurohumoral role is suggested by several findings. Prostaglandins are widely distributed in the central nervous system1, and in the rat cerebral cortex they are localized in synaptic vesicles2. They are released from the feline cortex3 and possibly cerebellum and ventricles4,5. In addition, prostaglandins have effects on the central nervous system of cats and chickens6,7. We decided to investigate the effects of prostaglandins on the isolated toad spinal cord because the preparation is convenient for studying direct actions of drugs on a neuronal pool. Furthermore, prostaglandins are released from the frog spinal cord on stimulation of the hind limbs8, suggesting that they are involved in synaptic transmission in amphibians.

Direct observation of toad bladder response to vasopressin.

Abstract: It has been suggested that the lateral intercellular space is a pathway for transepithelial water flow in several tissues. Fundamental to this postulate is the observation that coincident with accelerated net fluid transport, either coupled to active electrolyte transport as in the gallbladder (1, 2), or due to passive water flow along osmotic gradients as in the collecting tubule (3, 4) and anuran membranes (5, 6), the lateral intercellular spaces widen . To correlate morphologic changes with fluid transport the epithelium is usually fixed with aldehydes or osmium tetroxide in preparation for electron microscopy. There has been no uniformity in the manner of applying the different fixative solutions to the different tissues . Water translocations may occur during the period of primary fixation, resulting in distortions of the lateral intercellular spaces unrelated to the physiologic function of the viable tissue (7) . The problem of fixation artifacts, specifically with regard to changes in the size of the intercellular channels, can be obviated by observing the effect of hormone on the living tissue directly (3, 4) . In the present report we describe a simple method to observe directly the effect of accelerated hydrosmotic flow on the size of intercellular spaces in the isolated bladder of the toad, Bufo marinur.

Degranulation of endothelial specific granules of the toad aorta after treatment with compound 48/80

Abstract: Incubation of isolated toad aortas in Ringer solution containing compound 48/80, a histamine liberator, resulted in marked degranulation of endothelial specific granules. Since incubation of these vessels in Ringer solution only did not show significant morphologic changes in these granules, these findings suggest that the degranulation was induced by histamine release from the granules, as in the case for mast cell degranulation, and that endothelial specific granules are a storage site of histamine in the toad aorta. The present morphologic data were supported by preliminary chromatography, which showed appreciable concentrations of histamine in the granule-containing pellets of subcellular fractions of homogenized toad aortas.